Telefonaktiebolaget Lm Ericsson (publ)

St-ericsson Sa

Aravindh Krishnamoorthy

Sajal Kumar Das

Leela Srikar Muppirisetty

Rainer Walter Bachl

Thomas Wagner

Deepak Menon

A technique for performing channel estimation for a wireless communication channel is provided. A determining circuit determines a channel condition for the wireless communication channel. A filtering circuit applies an estimation filter to reference signals transmitted on the wireless communication channel. The filter estimates coefficients for a subset of Resource Elements transmitted on the wireless communication channel. The subset is chosen depending on the determined channel condition. An interpolating circuit interpolates the estimated coefficients for Resource Elements that are not included in the subset.

Channel estimation for a subset of resource elements of a resource block

The present subject matter discloses a system and a method for estimating a frequency offset in communication devices. In one embodiment, the method of estimating a frequency offset in a communication device comprises generating a reconstructed signal based at least in part on a channel impulse response (CIR) corresponding to a received signal. Further, a normalization matrix is determined for the reconstructed signal. Thereafter, based at least in part on the normalization matrix and the reconstructed signal, the frequency offset is estimated such that the frequency offset corresponds to a maximum normalized-correlation between the reconstructed signal and the received signal.

Frequency offset estimation in communication devices

The present subject matter discloses a system and a method for processing of channel coefficients of networks. In one embodiment, the method includes ascertaining at least one probable synchronization position of a received sequence and projecting, by oblique projection, at least one given noise basis vector spanning a given noise space onto the null space, so as to determine a channel impulse response at the at least one probable synchronization position. Based on a criterion related to the channel impulse response, a synchronization point for the received sequence is identified from the at least one probable synchronization position. The method also includes determining the noise contribution at the synchronization point and determining the noise coefficient of the at least one given noise basis vector based on the noise contribution so as to recover a signal substantially similar to the originally transmitted signal.

Processing of channel coefficients of a network

Methods and apparatus are disclosed for estimating a quality of a received data frame in a trellis decoder. The decoder utilizes a trellis diagram to depict the states and stages the decoder transitions through in search of a sequence of bits that closely resemble the received sequence. In the trellis diagram, each state at one stage is connected to a state at the next stage by a branch and a group of connected branches form a path. The decoder selects a winning path by comparing path metrics computed for each of the paths in the trellis diagram and outputs a most-likely sequence of hard bits from the winning path. A count of non-ideal branches over the winning path can be used for calculating the frame quality of the received data frame or the burst quality of a data burst in the received data frame.

Frame quality estimation during viterbi decoding

A high-sensitivity receiver may be made by using multiple demodulators to demodulate a given signal. For example, the receiver may use a first demodulator to demodulate an input signal into a first sequence of soft bits and a second demodulator to demodulate the same input signal into a second sequence of soft bits. The two sequences of soft bits may then be compared and combined to create a sequence of hard bits. For example, in some embodiments, a soft bit combiner may combine the two sequences of soft bits into a third sequence of soft bits, which may then be input into a decoder to produce the final decoded hard bits. The secondary demodulator may be less complex, less expensive, demand less power, and/or require fewer computational resources when operating, than the first demodulator.

Systems and methods for demodulating a signal

Described herein are various methods for a communication device (e.g., a mobile station) receiving an AQPSK modulated signal (e.g., a VAMOS signal) to estimate a subchannel power imbalance ratio (SCPIR). Advantageously, the methods are not computationally complex and do not suffer from poor numerical performance.

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Bengaluru, India

Aravindh Krishnamoorthy